As Windows 11 continues to evolve, users may not have noticed the significant increase in the size of its updates. Monthly cumulative updates are frequently surpassing 4GB, with some even approaching 5GB. A deeper dive reveals that one of these updates can expand to nearly 9GB once extracted. This analysis focuses on updates sourced from the Microsoft Update Catalog, representing the original size before any modifications for specific hardware or previously installed updates.
The prevailing assumption for this growth often points to the integration of artificial intelligence features, such as Copilot and semantic search. While AI does play a role, it is only part of the broader narrative surrounding the construction and delivery of Windows updates. The real challenge lies in how new features are packaged, compressed, and distributed across a multitude of systems.
Why have Windows updates grown in size?
Microsoft has shifted away from delivering small, isolated patches, opting instead for what are known as Latest Cumulative Updates (LCUs). This means that the mandatory monthly security update, commonly referred to as Patch Tuesday, encompasses not only the fixes for that month but also all previous fixes. Consequently, installing the latest update ensures that systems are fully up to date, even if earlier updates were skipped.
This approach enhances reliability but inadvertently leads to larger update sizes over time. Even if a user’s PC requires only a minor fix, the update package still includes the entire set of changes necessary to bring any system up to the current version.
To address this issue, Microsoft introduced Checkpoint Cumulative Updates with Windows 11 24H2. This strategy involves establishing periodic “checkpoints” that serve as new baselines, allowing subsequent monthly updates to include only changes since the last checkpoint. While this concept appears promising, the practical outcome has been mixed. Following the establishment of a checkpoint in September 2024, updates remained relatively small until the May 2025 update, which saw a dramatic increase in size, jumping to over 4GB in the catalog.
Why Windows 11 May 2025 update tripled in size?
A closer examination of the May 2025 cumulative update reveals that its decompressed size surged from approximately 6.5GB to nearly 9GB compared to April. Interestingly, the compressed MSU file increased by around 3GB, while the decompressed file only grew by 2.5GB. This anomaly raises questions, as one would typically expect compression to reduce the size of the package.
Within this update, there are tens of thousands of files—over 28,000 in total—but none appeared unusually large. The most significant file size was still attributed to the msedge.dll from previous months. The April 2025 cumulative update was 1,287 MB, while May’s update ballooned to 4,369 MB. Our analysis indicated the presence of numerous new MSIX files related to semantic search and on-device AI, contributing to the substantial size increase.
AI is in the package, but not on your PC
Windows Update employs applicability logic, which means it assesses your hardware configuration before downloading updates. This results in a smaller download size for most users. For instance, a fresh installation of Windows 11 25H2 on a virtual machine required only about 1.7GB from a 4GB+ catalog package, as many components were not applicable to that machine.
Initially designed for high-performance PCs with specialized hardware, the Semantic Search components have expanded to include support for a wider range of systems. This expansion leads to larger update packages, even for machines that will never utilize those features. A potential solution would be to deliver AI models and Semantic Search components through the Microsoft Store or as optional downloads, but Microsoft has yet to implement this approach.
Why can’t Microsoft just send exactly what changed in an update?
Given that Windows can identify what each system requires, one might wonder why Microsoft does not simply package only the necessary components. While differential updates exist, allowing Windows to pull only the changed portions of binaries, the inefficiency lies within the package structure itself.
True modular updates present significant challenges at the scale of Windows, which serves over a billion users with a vast array of hardware configurations. Each update must maintain backward compatibility and be safe for deployment across diverse systems. Missing a single dependency could lead to catastrophic failures, such as a system failing to boot.
In enterprise environments, the situation is even more complex. Tools like WSUS and Configuration Manager require full cumulative updates, leading to substantial storage and distribution challenges. As a result, while individual home users may experience smaller downloads, enterprises face a growing burden of data movement and storage costs.
Why Apple gets away with smaller updates
In contrast, macOS incremental updates typically range from 1 to 3GB, with larger updates reserved for major releases. Apple’s control over its entire hardware stack allows for stricter compatibility rules and more aggressive dropping of older components. Furthermore, Apple does not adhere to a fixed monthly update schedule, which provides greater flexibility in bundling changes.
What’s happening to Windows 11 updates in the enterprise infrastructure
For home users, the actual download sizes are often less daunting than catalog figures suggest, thanks to delta logic and applicability checks. However, enterprises do not benefit from this flexibility, as they must download and store full packages every month, leading to compounded storage issues.
The yearly storage cost for enterprises has escalated dramatically, with the average per architecture per distribution point rising from approximately 11 GB in 2024 to 52 GB by 2026. This trend indicates a significant increase in storage requirements, which is concerning for organizations managing multiple distribution points.
How to check what your PC is downloading during an update
To gain insight into the actual download size, users can navigate to Settings > Windows Update > Advanced options > Delivery Optimization > Activity monitor. This feature reveals the exact amount of data downloaded from Microsoft, local peers, and the cache. For further details, the Event Viewer contains Windows Update logs, and executing Get-WindowsUpdateLog in PowerShell generates a readable log file.
Ultimately, the size of Windows updates stems from a commitment to reliability across diverse configurations. While Microsoft is working to minimize what reaches devices, the inherent design of the update packages continues to grow, leaving users to ponder the future of update management in the Windows ecosystem.
